SACBROOD. 47 



did not reach the brood within a month or six weeks, it is not prob- 

 able that the disease would be transmitted under such circumstances 

 (p. 41). Should the dead larvae or any fragments of them be car- 

 ried out of the hive, the virus would have to be returned to the 

 hive, as a matter of course, before further infection of the brood 

 could take place from such infective material. 



It is left to be considered in what way the infective material if 

 removed from the hive might be returned to the brood and infect 

 it. Should any material containing the virus reach the water sup- 

 ply of the bees, or the flowers visited by the bees, it is within the 

 range of possibility that some of the living virus might be returned 

 to the hive and reach healthy young larvae. 



While out of the hive, however, the virus must withstand certain 

 destructive agencies in nature. Under more or less favorable cir- 

 cumstances it would withstand drying alone for a few weeks (p. 37), 

 but if exposed to the sun it might be destroyed in a few hours, (p 38). 

 If the virus were subjected to fermentation it might be destroyed 

 within a week (p 43), and if subjected to putrefaction, within two 

 weeks (p. 44). 



The experimental evidence indicates that the virus, once out of 

 the hive and freed from the adult bees removing it, during the 

 warmer seasons of the year, at least, has but little chance of being 

 returned to the hive and producing any noticeable infection. In the 

 experimental apiary (PL III) a large number of colonies have been 

 heavily infected with sacbrood through experimental inoculation, 

 and no infection was observed to have resulted in the uninoculated 

 colonies. If throughout the main brood-rearing season the usual 

 source of infection were the flowers or the water supply, a quite 

 different result would be expected. 



Tentatively it may be concluded, therefore, that the probability of 

 the transmission of the virus of sacbrood by way of flowers visited 

 by bees, practically considered, is quite remote, being, however, to 

 a limited extent theoretically possible. 



It would seem that there is a greater likelihood of the water supply 

 being a source of infection than flowers. The chances for infection 

 from this source, should it occur at all, would be greater in the 

 spring, as at such a time the quantity of infective material in dis- 

 eased colonies is greater, increasing the chances that some of it 

 might be carried to the water supply and contaminate it, and fur- 

 thermore, the destructive agencies in nature are at this time less 

 efficient. 



Bees drifting or straying from infected colonies to healthy ones 

 must be thought of as possible transmitters of the disease. That 

 the disease is not spread to any great extent in this way is evidenced 



